I think the problem is is that coding is not wholly a 'writing code' problem. It's a translation from idea to outcome. Often I think the bad code generated by an LLM is less to do with it's 'ability' and more to do with an instruction that hasn't adequately accounted for the possibility of what code satisfies the criteria. I'm not sure how a newer model can improve on this per se - sure there will be imrpovement on outright mistakes but for me at least, that's been and gone with more or less with any model released in te last 6 months.